The present invention relates to a profiled spacer for a spacing frame and, more particularly, to a spacer made of a material capable of elastic-plastic deformation with low thermal conductivity, to be mounted in the border region of at least two spaced-apart plates, particularly transparent panes for insulated window units, and capable of forming an intermediate space between the panes, whereby the profiled spacer comprises a chamber which in its walls has a plastically deformable reinforcement element extending in a longitudinal direction of the profile.
Within the framework of the invention, elastically-plastically deformable materials are materials in which elastic restoring forces act after the bending process, as is typically the case in plastic materials, whereby a part of the bending takes place with a plastic, non-reversible deformation.
Plastically deformable materials are materials wherein practically there is no action of any elastic restoring forces after bending, as is typically the case in the bending metals beyond their yield limit.
Materials with poor thermal conductivity or heat-insulating materials comprise materials which, compared to metals, have a clearly diminished thermal conductivity, which means a thermal conducting reduced by at least a factor of 10. The thermal conductivity values are typically of the order of magnitude xcex≈5 W/(mxc2x7K), and preferably smaller than 1 W/(mxc2x7K), and even more preferably smaller than 0.3 W/(mxc2x7K).
Within the framework of the invention, the plates of the insulation-plate unit are normally glass panes of inorganic or organic glass, although the invention is not limited to them. The panes can be coated or refined in any other way, in order to impart special functions to the insulating window unit, such as increased thermal insulation or sound insulation.
Spacer frames have the important task of keeping the panes of a window unit spaced apart, to insure the mechanical strength of the unit and to maintain the intermediate space between the panes free from external influences. Primarily in insulating window units with a high thermal insulating capability it can be seen that the heat conductivity characteristic of the marginal interconnection, and thereby of the profiled spacer which constitutes the spacer frame, needs spacial attention. A decrease of the thermal insulation in the border region of an insulating window unit meant to have a high thermal insulation capability because of the use of common metallic spacers has been proven many times.
For this reason, besides metallic profiled spacers, for quite some time profiled spacers of plastic material have also been used, in order to utilize the low thermal conductivity of such materials. However as a rule such materials are less resistant to diffusion than metals. Since the humidity in the surrounding air has to be prevented from penetrating into the intermediate pane space and the escape of filling gases, such as argon, krypton, xenon and sulfur hexafluoride which fill the intermediate pane space has to be kept within minimal limits, as a rule special measures have to be taken when plastic profiles are used. For this reason the DE-A 33 02 659 for instance proposes to provide a profiled spacer with a vapor barrier in the form of a metal foil or a metallized plastic foil applied over the plastic profile.
Plastic profiles have the further disadvantage that they can be bent only with difficulty or cannot be bent at all to form spacer frames made in one piece. Therefore plastic profiles are generally produced in straight bars cut to the sizes required by the respective window unit and interconnected by several corner connectors to form a spacer frame.
DE 93 03 795 U1 discloses reinforcement bodies extending in the longitudinal direction of the profile, which are embedded exclusively in the inner wall of the spacer profile facing the intermediate pane space. In this way the reinforcements are supposed to support the stability of the inner wall facing the intermediate pane space, which is endangered by UV-radiation and heat expansion. The bending behavior of the aforementioned profile is not discussed in this reference.
DE-U-92 14 799 and GB-A-2 162 228 disclose spacer profiles of the kind mentioned in the introduction with a single reinforcement element extending from an outer corner area of the profile over its outer wall into the other outer corner area and which obviously does not allow for the production of an one-piece spacer frame through cold flexion.
It is the object of the present invention to provide a thermally insulating spacer profile which can produced on a large scale in a cost-efficient manner, from which it is possible to simply produce a spacer frame made in one piece. It should be possible to produce the profile through cold flexion, particularly with conventional, albeit slightly modified bending devices, and if necessary with a little heating, to make it bendable enough, without the occurrence of undesirable deformations.
This object is achieved with the spacer profile having a chamber and separating the window panes. The reinforcements are located at the corners of the chamber or only in the lateral walls. According to the invention the lateral walls of the chamber are each provided with at least one reinforcement element.
Since in the spacer profile of the invention the reinforcement elements are embedded in the lateral walls of the spacer profile made of materials with low thermal conductivity, or are arranged on their surface, therefore not creating any direct thermal contact between the panes, the thermal conductivity from one pane to the other through the spacer profile is influenced by the reinforcement elements very little. On the other hand, due to their plastic deformability, as well as to the arrangement in area of the lateral walls of the profile, they contribute considerably towards achieving the object of the invention.
Due to the arrangement of the reinforcement elements according to the invention, in the selection of the elastically-plastically deformable materials with poor heat conductivity, constituting the main component by volume of the profile, it is possible to use also materials whose plastic deformability is not of the first order, and even almost perfectly elastic materials, when these offer advantages from the point of view of heat insulation. On the other hand, the reinforcement element can be selected targeting their plastic deformability and their characteristics during the bending process, without subjecting their dimensions or their material to substantial limitation with regard to the level of their thermal conductivity.
For the bending process commercially available bending devices without significant modifications can be used.
The profile of the invention is designed as a hollow-chamber profile, whereby the chamber is normally filled with hygroscopic material and whereby water-vapor permeable areas, such as perforations, in the inner chamber wall facing the intermediate pane space make a vapor and humidity exchange possible between the intermediate pane space and the chamber. In this way the humidity content in the intermediate space between the panes is kept at a low level, in order to avoid condensation at low temperatures. Alternatively, the spacer profile can also have a U-shaped cross section open towards the intermediate pane space, when care is taken that the drying agent is firmly anchored in the chamber, e.g. through adhesion.
The cross section of the reinforcement elements can have various shapes. So for instance these elements can be in the form of wires, which makes simple and cost-effective production possible.
Further the reinforcement elements can be flat or corner profiles. This insures a high degree of shape stability, particularly in the cross section corner areas of the spacer profile. It is also possible to combine wires and flat or corner profiles in a spacer profile.
Generally the reinforcement elements are made of metal or of a metal alloy, preferably aluminum or an aluminum alloy. As a result a particularly high degree of plastic deformability of the spacer profile and a particularly low resilience after bending are insured.
The diameter of the wires is preferably smaller than 3 mm, particularly approximately 1 mm, while the flat or corner profiles have generally a thickness of less than 3 mm, preferably a thickness of less than 1 mm. With this wire diameter or thickness of the profile, a good plastic deformability at low material consumption and low weight of the spacer profile is insured.
The reinforcement elements are preferably arranged in cross section corner areas of the spacer profile. These areas, which are particularly stressed during the bending process through stretching or compression, are very sensitive and damage occurs during the bending process particularly in these areas in the case of conventional profiles. The reinforcement elements in these areas prevent the occurrence of such damage. If reinforcement elements in the form of wires or corner profiles are arranged at least in the areas of both ends of the two lateral walls, then the bending moment of resistance of the spacer profile is reduced in an advantageous manner, so that a particularly good cold flexion can be achieved.
In another preferred embodiment the flat or corner profiles extend substantially over the entire height of the side walls of the spacer profile. Because of the high bending moment of resistance resulting therefrom, the side walls have a particularly high stability, so that the occurrence of damaging deformation can be reliably avoided.
In another preferred embodiment, the cross sectional shape of the corner profiles provided in the cross section corner areas of the spacer profile correspond substantially to the cross section of these corner areas, for good protection of the spacer profile during the bending process and the general handling and high shape stability.
It is within the framework of the invention to provide reinforcement elements of different material inside the same profile. Also reinforcement elements of composite materials can be provided. The reinforcement elements can be made of different materials or have different thicknesses in their longitudinal direction or also over their cross section.
Thermoplastic materials with a thermal conductivity value xcex less than 0.3 W/(mxc2x7K), e.g. polypropylene, polyethylene-terephthalate, polyamide or polycarbonate have proven to be well-suited heat-insulating materials for the spacer profile. The plastic material can contain the usual filler, additives, dyes, agents for UV protection, etc.
Preferably a diffusion-proof layer is provided, which extends substantially over the entire width and length of the spacer profile and is made of a material with a thermal conductivity value xcex less than 50 W/(mxc2x7K). Metals, particularly tin plate or also stainless steel, have proven to be preferred materials for the diffusion-proof layer. Further the diffusion-proof layer can be made of plastic such as fluorine-containing polymers, polyvinylidene chloride or ethylvinyl acetate. The diffusion-proof layer can be applied through physical or chemical coating methods, such as for instance sputtering or plasma polymerization. Preferably it is materially bonded as foil with the material of the profile. Thereby the xe2x80x9cmaterial bondingxe2x80x9d means the permanent bonding of the two components of the bond, for instance through lamination, optionally by means of a bonding agent, through embedding or similar techniques.
The diffusion-proof layer is preferably arranged also in the area of the side walls.
For cost reasons and for technological reasons, the diffusion-proof layer is preferably applied to the outside of the outer chamber wall and optionally to its side walls. However it can also be arranged on the inside or be embedded in the walls. As a result the bending process can be even further simplified, depending on the bending device, since this way a direct contact of the mechanically sensitive diffusion-proof layer with the force-applying elements of the bending device can be avoided. Besides this way a durable protection of the diffusion-proof layer can be insured.
The diffusion-proof layer can be additionally provided with a protective layer, in order to extensively avoid for instance aging processes or radiation influences, or also damage due to mechanical stress.
In a window unit according to the invention with a spacer profile like the one described above, the spacer profile is preferably cemented to the inside of the panes with a butylene sealing material based on polyisobutylene.